Up to four NHS patients a week are losing their sight because hospitals cannot keep up with demand for appointments, a leading expert has warned.

Prof Carrie MacEwen, president of the Royal College of Ophthalmologists, said follow-up appointments were being delayed for months or even years, partly because NHS targets only relate to the initial consultation.

She said action urgently needed to tackle the "perfect storm" of rising demand caused by an ageing population requiring more long term care.